Spark-plug.



W E. SHERBONDY.

SPARK PLUG.

APPLICATION FILED APR-7,1913.

1 ,1 13,54 1 Patented Feb. 29, 1916.

WILLIAM E. SHERBONDY, OF CLEVELAND, OHIO, ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE.- BIGSBY ROTARY MANUFACTURING COMPANY, OF CLEVELAND, OHIO, A

COREORATTON OF OHIO.

SPARK-PLUG.

Specification of Letters latent. Patented Feb. 29, 1916.

Application filed April 7, 1913. Serial No. 759,329.

To all to ham it mayconcern Be it known/that I, lViLLIAn E. SHER- BONDY, a citizen of the United States, and resident of Cleveland, in the county of Cuyahoga and State of Ohio. have invented certain new and useful Improvements in Spark-Plugs, of which I hereby declare the. following to be a full. clear. and exact description, such as will enable others skilled in the art to which it appertains to make and use the same.

The objects of the invention are to provide a simple and eilicient and positively acting means for preventing the deposit and spreading of carbon or other conducting materials over the surface of the shell of a spark plug. where it is exposed to the products of combustion within the cylinder of an explosion engine. This deposit is often made to such an extent as to provide a conductor for the electric currentbetween the central electrode and shell. and thereby forms a shortcircuit of low resistance through which the electric current will travel in preference to traversing the air gap between the electrodes, where a greater amount of resistance will be encountered.

It is well understood that even a slight deposit ofcarbon connecting the electrodes of a jump spark plug will lessen the chi ciency of the spark, and larger accumulations will lead the current entirely away from the air gap, and no spark at all will be produced. The effect of heating the carbon film thus formed is also to increase the conductivity of the film. and the compression of the vapors or charge within the eviinder serves to increase the resistance to the electric current at the air gap, and thus when the engine is in use there is a constant tendency to decrease the efficiency of the spark. To overcome this depreciation in etficiency the present invention includes means for providing a projecting nipple or zone about the central electrode which will automatically free itself from deposits of conducting material, and thereby prevent the short circuiting of the electric current by means of conduction or arcing. This zone is obtained by means of a projecting member which will acquire a sutliciently high degree oftemperature from contact with the heated products of combustion in the cylinder to consume the deposits of con-- ducting material formed by incomplete com-- bustion andso fast as the gather thereon. This conducting material consists usually of deposits of carbon and oil.

The invention in its preferred form comprises a thin annular member of porcelain, steatite or other insulating and refractory material such as will be quickly heated by the exploded charge. and which projects beyond the bodv of the plug into the cylinder. The central electrode projects through an opening provided in this member, which made preferably of small diameter to assist in excluding the products of combustion from the inner walls of the shell. The

annular member is mounted upon, and preferablv integral with. a disk (which may be of-porcelainl and which forms a closure for the extremity of the shell.

The invention is hereinafter further described. shown in the accompanying drawings and specifically pointed outin the claims.-

In the accompanying drawings Figure 1 is a bottom view of the improved spark plug: Fig. 2 is a vertical central section of the lower part thereof: Fig. 3 is a side elevation of the closure for the shell and the attached heating element or member; Fig. l is a side elevation thereof.

In these views A. is the shell of the spark plug.

B is the central insulation.

C is the central electrode. which is mounted in the central insulation B.

D is the outer electrode.

E is the air gap, in which the arc is formed.

F is the heating element which forms a zone of non conducting material and which in its preferred form comprises a thin porcelain flange or ring projecting into the cylinder and preferably mounted upon a disk f which is seated in the extremity of the shell wall. The flange incloses acentral opening f through which the central electrode C projects, leaving preferably a narrow annular space 7 between the disk and electrode. This heating element F constitutes the important feature of the invention and extends into the cylinder close enough to the spark gap to become heated by concoat the remaining portions of the disk and-- pile upon the edge of the wall as indicated in Fig. 2 at T, but the extreme edge of the lip will be free from deposit and form a zone of non conducting material which the current cannot cross and hence the connec tion will be broken. The amount of conducting material entering the small annular opening f will not be sutlicientto cause any material coating of the inner walls of the shell, or enough to permit a short circuit to arise between the central electrode and shell, since if the annular opening 7 is of the proper size the heat acquired from contact with the member F will consume the deposits before they enter the recess in the end of the shell.

Having described the invention what I claim as new and desire to secure by Letters Patent is:

1. The combination with the shell and electrodes of a spark plug, of an insulating refractory disk forming a closure for the extremity of said shell, said disk provided with a thin annular outwardly projecting lip or flange providing an easily heated member encircling one of said electrodes.

2. In a spark plug, the combination with the shell having a recess, the central lnsufor said recess, and an annular insulating and refractory member forming a portion of said closure, and encircling said central electrode, said member projecting longitudinally of said plug into said cylinder and exposed to the heated gases in said cylinder,

and providinga zone of higher temperature than the body of the closure.

4. The combination with the recessed extremity of the shell of a spark plug for the cylinder of an explosion engine, and the cen tral and outer electrodes therefor, of a closure for the recessed extremity of said plug through which. said central electrode projects, an annular refractory member at the inner edge thereof, projecting into said cylinder beyond the walls of said spark plug, and forming a rim extending at an angle to said closure, and encircling said central electrode.

In testimony whereof, I hereunto set my hand this 27 day of March 1913.

IVILLIAM E. SHERBONDY.

In presence of IVM. M. Moxnois, CHAS. H. Draw. 

